Writes SQL and Python that is clean, readable, and follows team conventions without needing to be reminded.
Applies appropriate data quality tests to all pipeline work - not just as box-ticking but as genuine protection for downstream consumers.
Reviews own work critically before submitting - checking for edge cases, null handling, and performance concerns.
Writes clear documentation for pipelines, transformations, and data models so that others can understand and maintain them.
Identifies and flags technical debt encountered during delivery work, even when not expected to resolve it immediately.
Develops growing instinct for pipeline performance - identifying queries that will not scale and raising concerns early.